Melt processable copolymers of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP), known under the name FEP (that is, fluorinated ethylene-propylene copolymer), have useful properties such as chemical resistance, weather resistance, low flammability, thermal stability, and excellent electrical properties. Such beneficial properties render these fluoropolymers useful, for example, in articles such as tubes, pipes, foils, and films. Various embodiments of FEP copolymers have been reported useful as coatings for wires and cables. See, for example, U.S. Pat. Nos. 5,677,404 and 5,703,185, each to Blair; U.S. Pat. No. 6,541,588 (Kaulbach); U.S. Pat. Nos. 6,743,508 and 7,923,519, each to Kono; and U.S. Pat. Nos. 7,122,609 and 7,126,056, each to Earnest. Certain TFE and FEP copolymers have been reported to be useful as polymer processing additives. See, for example, U.S. Pat. No. 5,089,200 (Chapman et al.) and U.S. Pat. No. 5,010,130 (Chapman et al.).
Using perfluoroalkoxyalkyl vinyl ethers as comonomers with tetrafluoroethylene has been reported in U.S. Pat. No. 7,060,772 (Hintzer).